Studies on Thrombocytosis. I. Hyperkalemia Due to Release of Potassium From Platelets During Coagulation1

Remarkable elevation of the serum potassium concentration without associated manifestations of hyperkalemia was observed in a patient with an unexplained increase in the blood platelets (1). Studies of the phenomenon in this patient indi- cated that the excess of potassium was derived from the platelets during the coagulation of the blood. Hyperkalemia was encountered in certain other patients with thrombocytosis. In contrast, no striking elevation of the serum potassium con- centration was observed when normal platelets were concentrated in vitro.